Advanced communication devices are capable of seamlessly operating in a packet-switched (PS) internet protocol (IP) network domain as well as in a circuit-switched (CS) cellular network domain. To facilitate this capability, current third generation partnership project (3GPP) standards specify a IP multimedia subsystem (IMS) that allows a communication device, referred to as user equipment (UE), to initiate calls to both IP-only subscribers and to conventional circuit-switched telephony subscribers using either or both of the PS network domain and the CS network domain.